This proposal requests funding for an upgrade of the current Siemens MAGNETOM Trio 3T Human MRI System in the Harvard Center for Brain Science to the new state-of-the- art Siemens MAGNETOM Prisma Fit System. This upgrade will have a significant impact on the neuroimaging research of our NIH-funded projects. The objectives of those funded projects include elucidating the relationship between brain deposits of amyloid, memory impairment, and Alzheimer's disease; studying the atrophy in the elderly of brain regions involved in social cognition, and the development and aging of cognitive control over behavior; delineating the contributions of the hippocampus to episodic simulation and constructive memory; studying the biological basis of emergent increases in daily-life anxiety, and clinical anxiety disorders, in late childhood and early adolescence; and understanding the neural mechanisms involved in object ensemble representation. The upgrade will greatly enhance image quality, reduce scan times, and enable powerful new methods such Simultaneous Multi-Slice (multiband) acquisitions.